Valve actuating mechanism



June 15, 1943. R. SPENCER 2,322,172

VALVE ACTUATING MECHANISM Filed Sept. 1 1941 2 Eheets-Shet 2 PatentedJune 15, 1943 UNiTED STATE VALVE ACTUATING MECHANISM ApplicationSeptember 17, 1941, Serial No. 411,232

Claims.

This invention relates to improvements in valve actuating mechanisms,and particularly that type of valve actuating mechanism wherein a rockerarm is rocked by an operating cam for the purpose of imparting motion toa valve stem, as illustrated in United States Letters Patent Nos.2,209,480 and 2,226,985.

One object of the present invention is to pro-' vide means forminimizing wear on the operating cam and that portion of the surface ofthe rocker arm which is contacted or engaged by said cam.

In Patent No. 2,209,480, means are illustrated for forcing a supply oflubricant to the contacting surfaces of the rocker arm and its operatingcam, but the structure illustrated in that patent is such that, if thereshould be a momentary stoppage in the flow of lubricant, those surfacesmight become excessively hot and impaired by such heat, due to the factthat the parts normally operate at comparatively high surface speeds. Afurther object of the present invention, therefore, is to provide meansfor retaining a reserve supply of lubricant in the rocker arm for thesecontacting areas of the rocker arm and the cam.

More specifically, the invention contemplates the provision of alubricant reservoir orlubricant-retaining recess in the rocker arm, towhich reservoir or recess the lubricant is fed through a passage in thearm and in which recess there is a revolving member against which thecam engages, the lower peripheral portion of said member being submergedin the lubricant retained in the recess, whereby the wiping action ofthe cam causes the member to revolve and constantly advance a lubricatedportion of the periphery of said member into cam-engaging position.

A still further object is to provide a comparatively simple means forinsuring correct assembly of the rocker arm in the valve actuatingmechanism. Furthermore, as explained in Patent No. 2,226,985,diniculties have been encountered in maintaining a flat contact betweenthe surface of the rocker arm and the rocker arm cam, and a stillfurther object of the present invention is to provide means forpermitting the rocker arm to adjust itself to the surface of the cam,said means being so constructed as to not require the use of any smallstructural elements that might be difficult to assemble or which mightbe easily broken.

With these and other objects in view, the invention consists in certaindetails of construction and combinations and arrangements 0f parts, allas will hereinafter be more fully described and the novel featuresthereof particularly pointed out in the appended claims.

In the accompanying drawings- Figure 1 is a sectional View takenlongitudinally of the rocker arm, illustrating one form of the presentinvention;

Fig. 2 is a similar view showing the rocker arm depressed.

Fig. 3 is a plan view, partly in section, of the structure shown inFigs. 1 and 2;

Fig. 4 is a view similar to Fig. 1, illustrating a modified form of theinvention;

Fig. 5 is a plan View of the rocker arm of Fig. 4;

Fig. 6 is a sectional view on the line 6-6 of Fig. 4;

Fig. 7 is a sectional view taken on the line l| of Fig. l; and

Fig. 8 is an exterior, elevational view of a portion of the motorcasing, illustrating the bearing therein for the rocker arm mounting.

As illustrated in Fig. 1, the rocker arm i0 is pivotally supported in.the wall of the motor casmg I I, with its free end in engagement withthe valve stem 12, so that, as the arm is depressed by its operating cam13, the valve stem will be correspondingly depressed. As will beunderstood, when the high portion of the cam I3 rides away from itsengagement with the rocker arm, the valve stem [2 will be returnedupwardly by suitable spring devices (not shown). As more fullyillustrated and described in Patent No. 2,209,489, lubricant is fedthrough a passage M in the rocker arm to a cavity in which the valvestem engaging disc l5 is seated, and from this cavity lubricant isdistributed through a branch duct It to the contacting surfaces of thedisc l5 and valve stei I2. In said Patent No. 2,209,480, the valve stemengaging disc I5 is also provided with a second branch duct, indicatedat ll in the present instance, for supplying lubricant to the surface ofthe rocker arm against which the operating, cam engages. However, theconstruction in Patent No. 2,209,480 is such that, if there should be astoppage of any material duration in the feed of lubricant through therocker arm, the contacting surfaces of the rocker arm and operating camwould heat up to raise the temperature of those surfaces to a pointwhere the surface-hardening at those portions would be seriouslyimpaired. This difficulty is overcome in the present instance byproviding the rocker arm with a lubricant reservoir orlubricant-retaining recess in which there is a revoluble cam-engagingmember so positioned that its lower peripheral portion will always besubmerged in lubricant, whereby, under the influence of the cam tendingto turn said revoluble member, a freshly lubricated portion of thatmember will be constantly advanced into position to be engaged by theoperating cam. In the embodiment of the present invention illustrated inFig. 1, the lubricant reservoir or lubricant-retaining recess isindicated at 3, and lubricant is supplied to this recess from branchduct I! in the valve stem engaging member, through a duct IS) in therocker arm which communicates with a short section of tubing 20, whichprojects from the rocker arm into the lubricant reservoir or recess i8.J ournaled to revolve in said recess is a roller 2| against which thecam l3 engages. The roller 2| may be journaled on a cross pin 22 mountedin the side walls of the lubricant-retaining recess IS. AS will appearfrom an inspection of Figs. 1 and 2, depression of the rocker arm Ii!causes the duct H in valve stem engaging member to move into registrywith duct 19, under which circumstances a small quantity of lubricantwill be forced through those ducts, and through tube from which it willbe discharged into the lubricant reservoir or cavity H3. The lubricantwill accumulate in this cavity so that the lower portion of roller 2|will be submerged in the lubricant and, as the wiping action of the caml3 causes the roller to revolve, freshly lubricated portions of theroller will be constantly brought into position to be engaged by theoperating cam. The capacity of this lubricant reservoir or recess I8 issuch that, if there should be any appreciable stoppage in the feeding ofthe lubricant through the several lubricant passages, the accumulatedlubricant in the cavity I8 will be sufiicient to maintain properlubrication of the contacting surfaces of the roller 2| and cam 13 foran appreciable length of time.

In the embodiment of the invention illustrated in Figs. 4 to 6, thecam-engaging member takes the form of a disc 2| in lieu of a roller. Thedisc is loose in the cavity, being retained therein by reason of thefact that the cavity walls embrace more than one-half of thecircumference of the disc, and by the use of a detachable side plate 23,secured to one side of the rocker arm by suitable fastening means. ofthe disc has to make a comparatively close fit with the surface of thlubricant reservoir or recess, it is preferred that What might be termedthe bottom of that recess be formed with a groove 24, so as to insurelubricant in the re- I cess having access to a comparatively larg areaof the periphery of the disc. Also, the closeness in the fit of the discin the lubricant reservoir or recess renders the use of an overhangingtube, such as 20 in Fig. 1, impossible, so that, in this modified formof the invention, the lubricant is conveyed from the duct in the valvestem actuating member l5 to the recess by a passage 20 in the rockerarm, this passage 2!] preferably being so located as to be in registrywith the groove 24 in the bottom of the lubricant reservoir.

In Patent No. 2,226,985, the rocker arm is pivoted in a cylindricalmember which is adapted to rock in its bearing in the motor casing wall,so that the arm may accommodate itself or adjust itself to maintain aflat contact with the surface of its operating cam, and this rockingmotion of the member in which the rocker arm is carried is limited by a,pin in the casing wall loosely engaging in a recess in said cylin- Asthe periphery drical member. Such a construction presents somedifficulty in assembly, and the use of the pin for limiting the rockingmotion of the cylindrical member in which the rocker arm is carriedpresents a rather fragile structural element. In the present instance,the use of comparatively small arts, such as the pin referred to in thepreviously mentioned patent, is eliminated, and a substantial structurethat may readily be assembled is provided by having the rocker armpivotally carried in a member or mounting formed of two differentdiameters at different portions of its length, with these two portionsof different diameters arranged eccentrically of one another, the borein the casing wall being correspondingly formed to receive the member ofthis shape. For instance, as shown in Figs. 1, 7 and 8, the member inwhich the rocker arm is pivoted is formed for the major portion of itslength with a cylindrical surface 25 concentric with the axis on whichthe rocker arm is adapted to tilt to accommodate itself to the surfaceof its operating cam. Near its inner end, this mounting for the rockerarm is formed of a reduced diameter 26 arranged eccentrically of theportion of larger diameter 25. Similarly, the bore in the motor casingwall is formed with a portion of larger diameter, indicated at 27,corresponding to the portion 25 of the rocker arm mounting member, andwith an inner portion 28 of lesser diameter corresponding to theformation of the reduced portion 26 of the rocker arm mounting member.Due to the eccentricity of the smaller portion of the bore 28 withrespect to the larger portion 21 thereof, and the correspondingeccentricity of the two portions of different diameters of the rockerarm mounting member, the mounting member can be inserted in the bore inthe casing wall in one position only. Furthermore, the diameters of thereduced portion 23 of the bore in the casing wall and of the reducedportion 26 of the rocker arm mounting member are such that there issufiicient clearance between these two associated parts as to permit therocking member to turn or rock slightly in its hearing. In other words,the portions of larger diameter of the bore in the casing wall and ofthe rocker arm mounting member being arranged concentrically of the axison which the rocker arm is to be permitted to tilt, turning of saidmounting member and tilting of the said rocker arm is limited only bythe closeness of the fit between the smaller portion 25 of the mountingmember and the smaller portion 28 of the bore in the casing wall. Itwill be appreciated that the fit between the portions of larger diameterof the rocker arm mounting member and the bore in the casing wall shouldbe such that there will be no material play or looseness of the mountingmember in its bearing. The rocker arm bearing member is yieldingly heldin its bearing by a spring plate 29 carried on the cap 30 which servesas a covering for said member, this cap being secured to the casing wallby suitable fastening means 3|.

What I claim is:

1. In a valve actuating mechanism, a rocker arm having a lubricantretaining recess in the upper surface thereof with a groove in thebottom surface of said recess. and a disc loose in said recess free toroll on the grooved surface of the recess, said disc being adapted to beengaged by the actuating cam of said arm.

2. In a valve actuating mechanism, a rocker arm having a lubricantretaining recess in the upper surface thereof, a disc loose in saidrecess adapted to be engaged by the actuating cam of said arm, said discbeing free to be revolved by th wiping action of said cam, and a,lubricant passage in said arm for supplying lubricant to said recess.

3. In a valve actuating mechanism, a rocker arm having a valve stemengaging member therein and a lubricant supply duct thereincommunicating with the stem engaging surface of said member, said armalso having a recess therein located to one side of said duct and abranch passage extending from said duct to said recess, and a rotatablebearing member in said recess adapted to be engaged by a cam, saidrecess being closed to retain lubricant therein to a level above thelower peripheral portion of said bearing member.

4. In a valve actuating mechanism, a rocker arm having a recess in theupper surface thereof,

a valve stem engaging member in the bottom face thereof with a lubricantsupply duct extending through said arm and communicating with saidrecess and with the stem engaging surface of said member, and a rollerjournaled in said recess adapted to be engaged by the actuating cam ofsaid arm.

5. In a valve actuating mechanism, a rocker arm having a recess in theupper surface thereof, said recess being open at one side of said arm, adisc loose in said recess, and a retaining member spanning the open sideof said recess to prevent lateral escape of said disc, said arm having alubricant passage therein communicating with said recess and said recesshaving a groove in its bottom surface for distribution of lubricant tothe periphery of the disc.

LOUIS R. SPENCER.

